The long-term goal of this project is to understand the molecular mechanisms for the formation of sensory maps in the cerebral cortex. Our current focus is to test the hypothesis that reciprocal interactions between the thalamocortical projections and the neocortex are responsible for the formation of area-specific and topographic sensory maps in the neocortex. In Specific aim 1, we will characterize the spatiotemporal relationship between the thalamocortical projections and the formation of anatomically and molecularly distinct areas, which is a critical first step to test the above hypothesis. In Specific aim 2, by using conditional gene targeting, we will analyze the roles of thalamocortical projections in establishing area-specific features o the neocortex. SIGNIFICANCE:Studies of the interactions between the thalamocortical axons and the differentiating neocortex have been limited because of the lack of reproducible experimental systems to specifically manipulate either of the components. We will use conditional molecular genetic techniques of the mouse to explore these interactions. This study will provide insight into the pathophysiology of developmental disorders that may involve the thalamocortical system. In addition, a better understanding of the roles of sensory inputs in the development and plasticity of brain circuitry will improve therapeutic interventions to manipulate activity to encourage compensatory changes in both children and adults with brain damage. [unreadable] [unreadable]